Group of young Douglas-fir defoliated by Douglas-fir tussock moth. Troy, Oregon.
Photo by: Walter J. Buckhorn Date: September 18, 1946
Credit: USDA Forest Service, Pacific Northwest Region, State and Private Forestry, Forest Health Protection. Collection: Portland Station Collection; La Grande, Oregon. Image: PS-727
From Walter J. Buckhorn's The Second Memorandum on the Douglas-fir Tussock Moth Outbreak Near Troy, Oregon: "This memorandum is a detailed supplement to the memorandum of September 23, 1946, in which the Douglas-fir tussock moth outbreak near Troy, Oregon, was briefly reported. In review it may be recalled that the outbreak was found on August 20, 1946, when the pine beetle survey crew cruised the Troy check plot. On September 18 and 19 the writer made a general examination of the area and estimated that the infestation involved some 10,000 to 12,000 acres. Almost complete kill of the Douglas-fir and white fir had occurred on some 500 to 600 acres in patches ranging up to 50 acres. Because of the extremely rough terrain and the general lack of roads, the area could not be adequately examined from the ground within the time available; hence, it was recognized that the estimated acreage of infestation might be materially low. Reports of local residents indicated that 1946 was the second year of the outbreak. Heavy deposits of eggs throughout the examined area indicated that the tussock moth population was sill increasing and that considerable timber would probably be killed in 1947." Buckhorn's full report is located here: www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev7_015606.pdf
To learn more about this photo collection see: Wickman, B.E., Torgersen, T.R. and Furniss, M.M. 2002. Photographic images and history of forest insect investigations on the Pacific Slope, 1903-1953. Part 2. Oregon and Washington. American Entomologist, 48(3), p. 178-185.